The whole point of the extension is to improve access to the relatively isolate (in London terms) Old Kent Road area, and tie in to the ludicrous amount of development around Lewisham in recent years.The route in the consultation was not what I was intended, but it's fine enough. I was expecting it to travel via (at a brief context) Denmark Hill, East Dulwich, Honor Oak Park, Catford interchanges, Hither Green and Grove Park to Bromley North.
With the rerouting between Lambeth North and Elephant & Castle, could the current Bakerloo platforms be kept as turnarounds for short journeys (as with Queens Park and Stonebridge Park), or will it be demolished, or be preserved as heritage use?
I can easily imagine it'll be like the Victoria Line to Walthamstow (or Jubilee to Stratford); attempting to run short journeys just reduces the capacity of the line overall, and I can see a Lewisham extension sucking up a colossal amount of inner area demand that will require the full service frequency to serve there anyway. Plus keeping the existing Bakerloo platforms in service requires two sets of platform staff, and would not be accessible or of high capacity like new-build platforms would be.
However, I could imagine the existing Bakerloo platforms (and overrun tunnels beyond) being useful for stabling of stock and (like Charing Cross Jubilee Line platforms) as an emergency turnback during disruption or planned works.